It is known to make integrally backed square butt joints by gas metal arc welding. Two or three metal components are joined by this process. When three components are joined, two of them are placed in an abutting relationship along an abutting joint, with the third component lying behind the abutting joint. All three are then fused into a single weldment. When two components are joined, the first component of the two is placed in an abutting relationship with a first portion of the second component along an abutting joint, with a second portion of the second component lying behind the abutting joint.
A specific application is to make a bulkhead or deck by butt welding sheets or plates to each other, with stiffening elements, i.e. studs or joists, backing up the butt welded elements, behind the butt welded joints.
FIG. 1 shows a prior art arrangement 10 for making such a weldment. A first component 12 and a second component 14 are placed over a third component 16 with a joint gap 18 between the first component 12 and the second component 14. The components are then secured in that position. A consumable metal electrode 19 is placed over joint gap 18, electrode 19 being of a composition metallurgically compatible with component 12, component 14 and component 16. Typically, electrode 19 has a composition similar to the compositions of component 12, component 14 and component 16.
An electric potential is applied between electrode 19 and the components 12, 14 and 16. An arc is then initiated between electrode 19 and the components 12, 14 and 16. Molten metal from electrode 19, is superheated in the arc and is accelerated towards the joint gap 18, fusing with portions of components 12, 14 and 16. Depending upon the thickness of the joint, multiple passes may be required to build up a plurality of weld beads filling joint gap 18 and thus joining components 12, 14 and 16. A significant expense of this type of welding is that a sufficient quantity of the consumable electrode 19 must be supplied to fill joint gap 18. In addition, the extra number of weld passes and the associated increase in the amount of weld metal and welding heat input per linear length can lead to extra weld induced distortion of the weldment.
FIG. 2 illustrates a prior art arrangement 20 for making an integrally backed square butt joint comprising a first component 12 and a second component 22, the second component 22 having an abutting portion 24 and an underlying portion 26; which underlies first component 12. As before, a joint gap 18 is provided to facilitate welding of component 12 to component 22.
FIG. 3 illustrates a prior art arrangement 30 for making an integrally backed square butt joint comprising first component 32, second component 34 and third component 16, third component 16 underlying first component 32 and second component 34. Arrangement 30 provides a V-shaped joint gap 38 which facilitates the welding process.
FIG. 4 illustrates another prior art arrangement 40 which is for making an integrally backed square butt joint comprising first component 32 and second component 42. Second component 42 includes an abutting portion 44 and an underlying portion 46. As before, arrangement 40 provides a V-shaped joint gap 38 which facilitates the welding process. A significant expense of these prior arrangements having a V-shaped joint gap is due to the requirement for joint preparation, by machining or cutting.
Also, for all of these prior art arrangements, a sufficient quantity of the consumable electrode 19 and welding power must be supplied to fill the joint gap, 18 or 38. Also, welding-induced distortion may occur due to the large amount of metal that must be filled into the joint gap, 18 or 38. Furthermore, a rather wide weld bead results from either of these arrangements.